1. Field of the Invention
This invention relates to gyroscopic flying devices.
2. Description of the Prior Art
The prior art discloses various tubular devices having a longitudinal axis, which are thrown through the air with a spinning motion in the direction of the longitudinal axis.
An early example was disclosed in U.S. Pat. No. 3,264,776 to Morrow (February 1966). In Morrow, a straight, hollow tube with unbalanced weighting toward the leading end is propelled with a rotational motion about its longitudinal axis. A slight taper extends from the trailing end to the leading end on both the interior and external surfaces of the tube. The tube is provided with a forward annular weighted area, such that its center of gravity is located within the leading one-half to one-third of the tube. The ratio of length to diameter (L/D) is also considered to be important, with the greatest stability occurring where L/D is around 1:1 to 1:2.
U.S. Pat. No. 4,151,674 to Kahn, et al. (May 1979) claims improved aerodynamic performance by incorporating a ledge along the forward edge of the cylindrical body. The rearwardly directed ledge is claimed to reduce drag and move the center of gravity to the forward quarter of the total length. Best performance in Kahn type devices was reported with the center of gravity placed at about 25% of the distance from the leading edge.
U.S. Pat. No. 4,246,721 to Bowers (January 1981) teaches the use of an annular recess on the outer surface of the hollow body adjacent the leading edge, together with an annular ridge formed on the adjacent inner wall. In addition, a weighted annular ring is adjustably positioned within the cylinder to permit ready modification of the center of gravity. Modification of the center of gravity is said to change the aerodynamic characteristics so as to produce several curvilinear flight paths.
U.S. Pat. No. 4,790,788 to Hill (December 1988) states that the above-cited devices have not had much commercial impact because desired aerodynamic characteristics are easily lost, and that the prior devices have erratic, unpredictable and inconsistent flight characteristics. He allegedly achieves consistent flight by improving aerodynamic characteristics in a dimensionally constrained design by placing a relatively thick peripheral ring at the laden edge of a short tube body. In addition, the leading edge of the ring is chamfered while the trailing edge fairs smoothly into the rear portion of the tube. Hill further states that the L/D ratio must be held between 0.8 and 0.74, and the ratio of leading end to trailing end weight must be about 2.2. These requirements place the center of gravity at substantially the intersection of the forward and rearward body sections.
U.S. Pat. No. 4,850,923 to Etheridge (July 1989) also notes limitations and short-comings of prior art devices. He claims to improve flight by further improvements to design parameters. Among other things, Hill teaches devices in which the outer surface inclines radially outward and rearward at a 16-degree angle in order to increase lift. Hill also teaches that the ratio of leading area weight to trailing area weight should be substantially between 2.2:1 to 2.5:1, which corresponds to an L/D ratio of about 0.86.
In 1992 the present applicants filed U.S. patent application Ser. No. 07/827,091. The grandchild of that application, U.S. Pat. No. 08/573,241, is expected to issue in 1998 as U.S. Pat. No. 5,816,880. In U.S. Pat. No. 08/573,241, the present applicants disclose that superior flight characteristics are obtained through the combination of D/L ratio .gtoreq.1.5 (L/D&lt;about 0.66) and a center of gravity at least 70% of the distance from the following end to the leading end. It was also disclosed that it is advantageous for the weighted portion to have a thickness of .ltoreq.0.4 inches, and for both the leading edge and the trailing, non-weighted region to have a thickness of .ltoreq.0.1 inches.
Embodiments disclosed in the 1992 disclosure are commercially successful in the toy markets of many countries. However, further improvements in the toy markets, and especially expansion into commercial and military markets, requires a greater understanding of the interactions among the various parameters than has previously been set forth.